Mixed-signal integrated circuits, for example today's advanced mixed signal integrated circuits, may have a number of analog subsystems. The analog subsystems may be used, for example, for low-power, multi-Gigahertz signal processing. For example, a power amplifier for use in a communication system may have an analog pre-distortion circuit for reducing distortion or non-linearities caused, for example, by memory effects, power amplifier self-heating and the decoupling of a power amplifier from a power supply. Such analog subsystems may pose several design challenges. For example, three such design challenges for analog subsystems of mixed signal integrated circuits may include random transistor mismatches, process-, voltage-, and temperature-dependent performance variations, and low voltage headroom.
Digitally controlled analog cells have been developed to address such issues. For example, an analog pre-distortion circuit for a power amplifier used in communications systems is discussed in commonly assigned, pending patent application Ser. No. 12/257,292, which is incorporated by reference herein in its entirety. However, since such analog cells are subject to further inaccuracies or non-idealities due to various factors that affect performance, such as the design issues discussed above, their performance may be less-than-desirable or less than ideal. In addition, although such analog cells may be tunable, adjustable, or able to be calibrated and/or adjusted, such procedures may occur only sporadically, may disrupt operation, and may not occur automatically.
Accordingly, there is a need for an improved device or method for more-efficient monitoring and adjustment, self-monitoring and self-adjustment, or automatic adjustment or self-healing for mixed signal integrated circuits.